Process of preparing perforated metal articles



July 12, 1938. L. R. BEYNEN ET AL 2,123,297-

PROCESS OF PREPARING PERFQRATED METAL ARTICLES I Filed Dec'. 9, 1935lmrentors' Barnum/Marie vanflaz &

Wz'IIem vanae P02 dtt orne s Patented July 12, 1938 UNITED STATESrnocass or raeramc, raaroaa'ran METAL ARTICLES Laurens Rynhart Beynen,'Brummen, Bernard Marie van Dorp, Vorden, and Willem van de Pol, Loenen,Veluwe, Netherlands Application December 9, 1235, Serial No. 53,680 i Inthe Netherlands December 12, 1934 4 Claims.

For the manufacture of perforated metal articles by means of-galvanoplasty it has already beenproposed to use a master plate thesurface of which comprises portions that are electrically conducting andportions that are electrically nonconducting. In making such aplate ithas been proposed to employ as a starting material a copper plate actingas a cathode, in which plate small cups were formed by means ofphotoengraving.

These cups are filled with insulating varnish, after which the copperplate is placed in a nickel bath. The nickel layer which is then formedis allowed to grow until the little elements of insulating material atthe. edges of the cups are overhung by the nickel.

One of the drawbacks of this method is in the first place that the cupscannot be refllledwith insulating material, as this is prevented by theoverhanging edges of the nickel deposit. This not only nullifies thepractical value of the process, but it also renders impossible massproduction in factories, especially for the manufacture of sieves whichrequire a great number of equal and uniform perforations. If the masterplate after it has been finished proves to have cups that are not or notsufliciently filled with insulating material, the product will beuseless.

Another drawback of this known method is that the metal article obtainedby electrodeposition or electroforming on the master plate thus formed,will deviate considerably from the desired form, since the said depositwill deviate around the openings from the plane of the article andfollow the curved line of the nickel deposit around the edges of thecups. This fact alone limits the use of the said method. v

The present invention has for its purpose to improve these conditionsand to provide a master plate for the manufacture of sieves and otherperforated metal articles which is free of the said drawbacks, producesbetter sieves and renders possible mass production in factories. Byperforated metal articles are meant those articles that are providedwith perforations or recesses of any given form and dimensions extendingthrough the entire thickness of the material.

A master plate according to the invention likewise has a surfacecomprising electrically conducting portions and electricallynon-conducting portions, and which is to be used as a carrier for sievesor other perforated metal articles to be formed thereon and ischaracterized by the fact .that the non-conducting portions aresurrounded by lead for a lead alloy, mercury amalgam or some othermaterial the surface of which in a moistened, resp. dry or othercondition has the property to repel the insulating material or itscarrier which is to be applied to the non-conducting portions, or toform them. 7

This in the first place has the great advantage that it is now possibleto improve at all times the insulating portions of the surface by arefill of insulating material. This may be done in a very simple mannerby applying, e. g. by means of rollers, fatty printing ink (German:"Feder- 6 farbe") which will adhere to the portions to be insulated, butwill not adhere to the electrically conducting portions of the surface,since these portions are either naturally fat-repelling (mercuryamalgam) or rendered fat-repellent to the l insulating mater al or itscarrier either by moistenlng with e. g. Water (surface of lead or a leadalloy or material having a similar or an equivalent surface) or bytreatment by some other agent.

The portions which are retaining the fatty ink l or similar material maynow be dusted with asphalt or some other material which after melting orburning or some other treatment will constitute the desired insulatedportions on which no deposits of the copper, nickel or other material 2for the sieves will be formed.

The invention therefore is not limited to any given material. as it isbased on the novel idea that it is possible to fill or to replenish theinsulation cups when the plate is treated with an insulating material ora preparatory material that will retain the insulating material whichdoes not adhere to the electrically conducting material, which materialmay be pre-treated (e. g. moistened) for this purpose.

l 30 According to the invention there may be formed on the carrierconstituting the carrier for the portions having insulated surfaces andfor the portions having electrically conducting surfaces, first a highrelief design of insulating substance or insulating substance-containingmaterial, and subsequently between the insulating portions 9. layer ofelectrically-conducting material as a carrier for the articles to beformed. The carrier which may be of copper may be slightly etched afterthe 4 formation of the high-relief design layer and prior to theapplication of the conducting layer around the parts of this designlayer.

After the application of the electrically conducting layer the saiddesign layer may be partly 45 or almost entirely removed, e. g. with theaid of hot lye, and the cups may be filled with fatty ink (the so-calledFederfarbe) and with asphalt, resin, copal resin, copal varnish or someother insulating material, owing to the above mentioned 50 I may beformed on the master plate in different ways e. g. by electroforming, orby cathodic atomization depending on the nature of the material of whichthey are going-to consist and of the purpose which they are to serve. a

It has been found in practice that both the layer comprising theportions which are to form the electrically-conducting surface, and thematerial for the sieve may be obtained in a satisfactory andadvantageous manner electrolytically.

According to the invention the conducting portion of the master platepreferably consists of the surface of lead or of a lead alloy which hasthe property of taking and retaining water without preliminary grainingi. e. in a smooth condition, and when moist to repel fatty ink andsimilar fatty material. A surface of this nature may be obtained e. g.by applying on a smooth ungrained copper plate a deposit of lead, eitherby electrodeposition by spraying or by cathodic atomization.

The application of the present invention to the making of sieves may bestill further explained with the aid of an example.

A smooth, polished copper plate l-vide Fig. 1-which has been coveredwith a light-sensitive layer is exposed to light through a screen insuch a way that round, square or otherwise shaped light points areformed on the emulsion and that corresponding hardened spots are formed.The said layer is then developed and completely finished, so that afterwashing and drying of the same raised points 2 remain on the plate whichmay be burned into the plate to make them adhere better.

Between the design elements 2 which in the present example have theshape of points, the polished metal surface of the plate I lies exposedand this surface is very slightly etched. Subsequently a thin layer oflead 3 is formed by electrodeposition on the smooth conducting portion,the design elements in their quality of insulating points preventing thedeposition on the places covered by them.

The layer of lead I-vide Fig. 3consequently will form a thin metalnetwork corresponding to the desired appearance of the sieves that areto be produced.

The plate is then cleaned with sulphuric acid or/ and other means,moistened with water which adheres to the smooth lead surface and fattyink is then applied to the plate by means of rollers, the said fatty inkadhering to the design elements 2, but not to the water retainingsurface of the layer of lead 3. The plate is then dusted with asphaltpowder as a strengthening insulation material, which powder is held bythe fatty-ink retaining parts, the remaining powder being removed. Theasphalt which remains on the plate is melted. This treatment may berepeated once or more, according to desired height and strength of theinsulating points.

The master plate thus obtained "comprises smooth, electricallyconducting portions 3 and non-conducting portions 2, on which conductingportions the sieves 4 may be deposited in the desired thickness and thenremoved-.vide Fig. 4. If desired, afresh supply may be added to theinsulation cups or the insulation may be strengthened or renewed after acertain number of sieves or other perforated articles have been made.-

As a variation on the above it is also possible according to theinvention, after the layer of lead or similar conducting layer has beenapplied-but not before that timeto remove the hardened emulsion-formerlysensitive layerstill present by means of heated lye or in some othermanner, after which the fatty ink will adhere better; if desired afterhaving cleaned the plate with sulphuric acid or some other means. Theplate may also be treated with a tincture and other means, before thefatty ink is applied to the plate.

Instead of the fatty ink (German: Federfarbe") repeatedly mentionedhere, any other material is suitable that will form insulating spots.resp. that adheres to those places where the insulating material is tobe applied and that, at the same time will not adhere to theelectrically conducting portions. As stated above, the repulsive powerof the conducting portions may be intensified by moistening the samewith water or a strongly diluted acid, for which purpose said portionshave been made water-retaining. The invention however is not restrictedto the use of moistened plates.

Before making the article by electroforming, spraying, cathodicatomization or other electrodepositing methods, the plate may be treatedwith known or other agents in order to facilitate the removal of thearticle after it is made.

Modifications and improvements are possible within the scope of thepresent invention. Said invention not only comprises the process ofmaking a master plate of the kind described above, but also covers themaster plate itself, and the manufacture of sieves or other perforated,more especially, but not exclusively thin metal articles.

We claim:

1. The process of making perforated articles by electro-deposition whichcomprises placing a design on a metal base plate by means of anelectrically insulated light-sensitive emulsion, hardening the emulsionform said design, etching the plate in the areas other than covered bysaid design, depositing an amalgam on said etched areas, cleaning saidplate with an acid, coating said plate with fatty ink, the latteradhering only to the hardened design, dusting said plate with asphaltpowder which adheres only to said fatty ink, cleaning the non-adherentink and powder, melting and hardening said asphalt, electricallydepositing a metal on said plate, and stripping off said metal in theform of a perforated article.

2. The process of making perforated articles comprising the steps ofelectrically depositing a metal on the conducting portions of a masterplate having electrically conducting fatty printing ink repellentsurface portions and electrically non-conducting surface portionscomposed of non-conductive material superposed on fatty printing inkretaining portions, and stripping off said metal in order to obtain aperforated article.

3. The process of claim 2, which comprises depositing said metal arounda layer of non-conductive material which extends above said repellentsurface portions.

4. The process of claim 2, which further comprises co'ating the masterplate with fatty ink, fixing asphalt to said fatty ink retainingportions to repair damaged portions of the same, electrically depositinga layer of metal on said plate,

- and stripping off said metal in the form of a perforated article.

LAURENS RYNHART BEYNEN. BERNARD MARIE VAN DORP. WILLEM VAN m: POL.

